the Study of Persistent Organic Pollutants in Human Milk

Inclusion Criteria: * Primiparae; * 30 years of age or below; * Have normal pregnancy; * Breastfeeding one infant only, and not multiple pregnancy; * Resided in Hong Kong for at least 10 years immediately before the date of interview; * Available for sample collection within 3 to 8 weeks of delivery; and * Both mother and child should be apparently healthy and free from any known infectious or other diseases (e.g. clinical hepatitis, AIDs, HIV). Exclusion Criteria: * participants with previously diagnosed major diseases such as hepatitis, AIDS and other such diseases shall be excluded from the study